Silencer



H. P. MAXIM April 23, 1929,

SILENCER Original Filed Feb. 20, 1925 IAIN TOR.

A TTORNEYS.

Patented Apr. 23, 1929.

4 UNITED STATES [1,709,992 PATENT OFFICE.

HIRAM PERCY..MAXIM, F mTFORD, C(QNNECTICUT.

SILENCER.

Application filed February 20, 1925, Serial No. 10,665. Renewed September 7, 1928.

This invention relates to silencers such as are used for silencing the exhaust noises of internal combustion engines and is especially designed to be used in silencing the exhaust noises of small engines of the outboard type having one or two cylinders.

One object of the invention is toprovide a compact and light silencer of improved construction which effectually silences the exhaust with the minimum of back pressure.

Another object is to provide a silencer wherein the various improved features of construction and design contribute to the durability of same and to the production of an efiicient and reliable silencer at low manufacturing cost.

A still further object is to provide a silencer which, besides silencing the exhaust noises, is also adapted to silence somewhat the intake noises of the carburetor of small engines, and at the same time provide means to furnace heated air to the carburetor.

To the accomplishment of the above and further objects as will hereinafter appear,

the inventionconsists in the features of construction and in the combination and arrangement of parts which will be first described in connection with the accompanying drawings and then particularly pointed out in the appended claims.

but of slightly different diameters and are assembled together in concentric relation about a common axis. Preferably the inner and intermediate shells 1 and 2 are provided with annular raised portions or ridges 4, 4 and 5, 5 respectively, located preferably adjacent both the ends thereof. These ridges may be conveniently formed by upsetting an integral portion of the shells. It will be noted that the inside diameter of each successive concentric shell is approximately equal to the outside diameter of the annular raised portions or ridges 4 and 5 on the next adjacent inner shell so as to lie in contact therewith. This insures an easy and compact assemblyof the shells, one within the other in concentric re lation and also provides an even spacing apart of same throughout their length and circum ference. ridges a, 4 and 5, 5 are located adjacent the ends of the shells 1 and 2 in slightly offset or out of line relation to one another so that they do not coincide or register with one another when the shells are assembled.

Each shell is provided at one end with a series of small openings annularly disposed thereupon, the openings preferably extending around a half of the circumference of each shell. The numerals 6 designate the openings on the inner shell 1; numerals 22, the openings on the intermediate. shell 2;"and numeral 23 the openings on the other shell 3. It will be noted that openings 6 are located on the opposite end of the mufiier to those on shell 2 and likewise the openings on shell 2 are on the opposite end of the mulller to those on shell 3; and also that the openings on adjacent shells are located on diametrically opposed sides thereof. 1

It .will be observed that the diameter of the inner shell 1 is many times greater than the space between the shells whereby a comparatively large inlet expansion chamber is. provided having its outlet through the narrow annular passageways between the shells. Surrounding the outermost shell 3 there is a shorter shell or sleeve 7 which is positioned at the end of the assembled shells which is opposite to the end of the outermost shell 3 having the openings 23 therein or in other words it surrounds a non-aperture'd portion of shell 3. The sleeve 7 is provided with small openings 8, 8 longitudinally disposed upon one side and a relatively large opening 9 upon a diametrically opposed side thereof. The opening 9 may be constructed in the form of a pipe 10 adapted to be connected to carburetor for a purpose to be hereinafter described. The sleeve 7 is also preferably formed with lapped ends 11 so as to provide a slight spacing of the sleeve 7 from the outermost shell 3, thereby forming an annular chamber or passageway 24 therebetween.

The open ends of the assembled structure re closed by removable annular plates or headers 12 and 13, each of which is provided with a circumferential flange 14 fitting tight- 1y over an end of the shell 3 and sleeve 7.

The raised portions or annular Preferably each end plate also has a hollow central protuberance which provides a small axial chamber 16 opening into the large central chamber 17 formed by the shell 1.

c Integral with each end plate there is formed flush ends of the shells and are also provided with a central. opening through which an axially disposed tie bolt 19; extends, thereby firmly holding the parts together, as shown in Fig, 2. It will be noted that the bolt 19 furnishes the sole means for holding said parts in assembled relation.

In operation, the exhaust gases and sound waves enter the large chamber 17 from either or both ends of the silencer, depending upon whether it is connected up to a oneor a two cylinder engine. After expanding in the chamber 17, the are constrained to pass through the small openings 6 in the shell 1 and into the annular passageway 20 formed between the two concentric shells land 2, then through the openings 22 in the shell 2 into the annular passageway 21 formed between the shells 2 and 3 and out to the atmosphere through the openings 23 inthe shell 3. The area of each series of openings 6, 22 and 23 in the various concentric shells l, 2 and 3 and the cross sectional area of each of the annular passageways 20 and 21 are each ap proximately equal to the cross sectional area of the inlet opening to the silencer so that the flow of the exhaust gases is not restricted to cause undue back pressure. After the sound waves expand in the chamber 17, only a portion of same escape through the openings 6 into the annular chamber 20, and from thence through the openings 22 into the annular chamber 21 whereby they are still further dissipated so that when they finally reach the atmosphere, through the openings 23, the noises of'the engine explosion are substantially silenced.

When the pipe 10 of the sleeve 7 is connected to the carburetor in such a way as to utilize the pipe 10 as the air intake of the carburetor, at each suction stroke of the engine, air is drawn into the carburetor through this pipe whereby the air is drawn from the atmosphere through the openings 8 of the sleeve 7, around the annular passageway 24 between the sleeve 7 and outer shell 3 and then through the pipe 10 to the carburetor. It will be obvious that afterv the first few explosions of the engine, the air thus drawn into the carburetor will be heated. Also the noises caused by the sudden intake of air into the carburetor will be substantially silenced, due to the circuitous passageway cylindrical shells which the sound waves originating at the air intake of the carburetor Wlll have to follow.

It will be understood that the silencer may be used either with or without the sleeve 7, the only change necessitated when used without the sleeve will be the use of an end plate having a circumferential flange of slightly smaller inside diameter'or by the use of a washer or ring to occu y the space usually taken up by the end of t e sleeve 7 in the circumferential flange 14s'o as to make the end plate fit tightly.

silencer fora one or two cylinder engine has been constructed in which the various parts are arranged and desi ed in a novelvmanner.- The improved si encer may be of very light construction, quickly assembled, and inexpensively manufactured. A further advantage is the provision whereby, with a simple and inexpensive appurtenance, the

air sucked into the carburetor ma be heated and the noises of the air intake 0 stantially reduced.

The invention has been disclosed in its preferred embodiment, and is not to be limited to the exact number of superimposed shells shown, or other details of the apparatus, as various changes therein may be made within the scope o the invention as hereinafter claimed.

What I claim is I .1. A silencer comprising an assembly of cylindrical shells of different diameters arranged concentrically about a common axis to form a plurality of annular passageways therebe'tween, spacing means in each passageway between two ad'acent shells comprising a circumferentiallyisposed bead offset from same subone shell for contact with the other shell, the

ofl'set beads of adjacent shells being so disposed that the high side of one will not fall into the low side of another. 7 2. A silencer comprising an assembly of cylindrical shells of different diameters arranged concentrically about a common axis to form a plurality ofannular. passageways therebetween, perforations in said shells to afiord communication between said passageways, the perforations in one shell being near its end and disposed only around one half a circumference thereof, the perforations 1n the next adjacent shell being near the oposite end and disposed only around the other alf circumference thereof, spacing means in each passageway between two adjacent shells comprising a circumferentially disposed bead offset from one shell for contact with the other shell, the offset beads of adjacent shells being so disposed that the high side of one will not fall into the low side of another when said shells are assembled.

3. A silencer comprising an assembly of of difierent diameters arranged concentrically about a common axis It will be thus observed that an improved to form a plurality of'annular passageways therebetween, spacing means in each passageway between two adjacent shells comprising a circumferentially disposed bead offset from one shell for contact with the other shell, the

offset beads of adjacent shells being so disposed that the high side of one will not fall into the low side of another when said shells are assembled, header members for abutting the ends of said shells, and a single axially disposed tie bolt for holding said shells and header members in assembled relation.

4. A silencer comprising an assembly of cylindrical shells of diilerent diameters and of equallength arranged concentrically about a common axis to form a plurality of annular passageways therebetween, spacing means in each passageway between two adjacent shells comprising a circumferentially disposed bead offset from one shell for contact with the other shell, the oflset beads of adjacent shells being so disposed that the high side of one will not fall into the low side of another when said shells are assembled, a header member having an annular plane surface for abutting the ends of said shells, one at each end of said assembly, and a single axially disposed tie bolt for holding said shells and header members in assembled relation.

5. A silencer comprising an assembly of shells arranged about acominon axis to form a plurality of passageways therebetween, spacing means in each passageway between two adjacent shells comprising a circumferentially disposed bead offset from one shell for contact with an adjacent shell, the offset beads of adjacent shells being so disposed that the high side of one will not fall into the low side of another.

In testimony whereof I have affixed my signature.

HIRAM PERCY MAXIM. 

